/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.springframework.web.reactive.socket.server.support;

import reactor.core.publisher.Mono;

import org.springframework.util.Assert;
import org.springframework.web.reactive.DispatcherHandler;
import org.springframework.web.reactive.HandlerAdapter;
import org.springframework.web.reactive.HandlerResult;
import org.springframework.web.reactive.socket.WebSocketHandler;
import org.springframework.web.reactive.socket.server.WebSocketService;
import org.springframework.web.server.ServerWebExchange;

/**
 * {@link HandlerAdapter} that allows using a {@link WebSocketHandler} with the
 * generic {@link DispatcherHandler} mapping URLs directly to such handlers.
 * Requests are handled by delegating to the configured {@link WebSocketService}
 * which by default is {@link HandshakeWebSocketService}.
 *
 * @author Rossen Stoyanchev
 * @since 5.0
 */
public class WebSocketHandlerAdapter implements HandlerAdapter {

    private final WebSocketService webSocketService;


    /**
     * Default constructor that creates and uses a
     * {@link HandshakeWebSocketService}.
     */
    public WebSocketHandlerAdapter() {
        this(new HandshakeWebSocketService());
    }

    /**
     * Alternative constructor with the {@link WebSocketService} to use.
     */
    public WebSocketHandlerAdapter(WebSocketService webSocketService) {
        Assert.notNull(webSocketService, "'webSocketService' is required");
        this.webSocketService = webSocketService;
    }


    /**
     * Return the configured {@code WebSocketService} to handle requests.
     */
    public WebSocketService getWebSocketService() {
        return this.webSocketService;
    }


    @Override
    public boolean supports(Object handler) {
        return WebSocketHandler.class.isAssignableFrom(handler.getClass());
    }

    @Override
    public Mono<HandlerResult> handle(ServerWebExchange exchange, Object handler) {
        WebSocketHandler webSocketHandler = (WebSocketHandler) handler;
        return getWebSocketService().handleRequest(exchange, webSocketHandler).then(Mono.empty());
    }

}
